Promises
by ThatApolloKid6123
Summary: Genocide Route Battle w/ Sans. San' POV what will happen when Sans finds out that Frisk wasn't evil all along, but that a demonic spirit (Chara) has taken over their body? What happens when he accidentally kills her when Frisk is Frisk? Why the heck isn't she reloading! (I suck at summary's)
1. Chapter 1

**Hey guys! Heh sorry i haven't uploaded for my Drabbles fanfic but I am just trying to type out where I want it to go. I kinda just started it and went along without planning much, as you guys probably noticed. Although lately i've really dove into the UnderTale fandom and i got this idea so, here it is! You might notice there are no typos(none that I've seen) and everything seems more organized, thats because i actually took the time to get an idea flowing, write it out and go over it a few times. Its also rather long heh. Anyways, if you guys want a chapter about Frisk and Sans talking and stuff and the end of the pacifist route leave it in a review or PM me. Otherwise this will stay a oneshot. One last thing, I see Frisk as either agender or female but in this fanfic i made Frisk a girl, so ya deal with it.**

 **Disclaimer: UnderTale belongs to Toby Fox not me.**

(Sans POV)

I sat in the shadow of a pillar in the Judgment Hall. What once was a rather beautiful hallway, was now the place I despised most. Heh. The stillness and silence was once comforting... Now its a constant reminder that I'm alone... That they're all dead...

I quickly wiped away the tears seeping out of my eye sockets. I couldn't cry now, otherwise I'll be weak when facing the demon. I stared down at Papyrus' signature scarf, of which I had wrapped around my neck bone when he... No. No depressing thoughts... Focus on your current task Sans. You have to stop Her. The Demon Spawn. The Demonic Child. The DIRTY BROTHER KIL- stop it Sans!

I was pulled out of my thoughts by the creak of the door opening.

They were here.

I took in a deep, inaudible breath, then stood up, ready to teleport when She was in the place. I wiped a sweat drop off as the Devil Saved.

She was walking unknowingly towards me, blade in hand. She was wearing that stupid sweater and heart-shaped locket that gave her the look of an innocent child. Until you looked at her blood-red eyes, bloody knife and sinister smile.

As soon as she was about two pillars away I teleported into the open, facing the one person I truly despised with all of my being.

Frisk.

"Well haven't you been busy?"

She just stared at me with a cold look. I decided to continue.

"I got a question for ya. D'ya think even the worst person could possibly... Change? That, maybe, everybody could be a good person if they try?"

Frisk stepped forward with a blank expression. I chuckled.

"Well then heres a question I rather like."

My white "pupils" disappeared, leaving my sockets dark and empty.

"Do you wanna have a bad time? If so, step forward for all I care. It'll be fun. For me.

The demon stepped forward. With that same blasted expression.

I muttered to myself, "Sorry old lady. This is why I don't make promises."

We entered a Fight.

I took on a fake peaceful expression. I had already basically planned out my words and actions.

"Ahh... Such a beautiful day outside. Birds are singin, flowers are bloomin. On days like this kids just like you..."

I opened my eyes, one socket was a black void. The other had a blue glow.

"Should be BURNING in hell."

Before my words could register, I sent _out_ sharpened bones at them, impaling their body and then disappearing, 45/92 HP.

I then sent out my Gaster Blasters, they were too frazzled to dodge any of the blasts and they immediately died.

Words popped up in front of me, giving me EXP and G.

I sighed and exited the battle. I prepared myself for the reset.

A flash of white came, along with a pain in my skull, they had reset and were trying to erase parts of my memory. I don't know how but I never forgot anything, as much as I wanted to, I never forget.

After the flash I found myself behind the pillar, wiping off the droplet of sweat again.

Alright so I have a few seconds to gather myself, I thought. Urghh. Every time a reset happened I wanted to regurgitate.

I sighed. Ok Sans, pull yourself together. You teleport... Now.

I teleported to the same spot as before.

I gave them a knowing smile.

"Hey, you look pretty frustrated about something. Guess I'm pretty good at what I do eh?"

Frisk seemed to get slightly irritated, but stepped forward to begin our second battle.

This time I decided to do the same thing as before, unfortunately She survived, but just barley.

Frisk: 24/92

They frowned. They seemed to hesitate over the options, Item and Fight. They decided to press Fight.

I dodged it with ease and they frowned angrily, understandable considering I'm the only monster alive who can dodge attacks. Coarse they didn't know that.

"You didn't think I would just stand there and take it did you?" I said mockingly.

I sent bones flying at them, they dodged a couple but ended up dying. I watched their soul shatter and got ready for the process to start repeating.

This time when I teleported I grinned mischievously and said,"Ahh now thats the expression of somebody whose died twice in a row. You look rather unsatisfied, how about we make it a third?

This time they dodged more, but still went down considerably.

43/92 They chose to Fight.

I threw a confusing mixture of blue and normal bones and throwing them off.

Their HP decreased more. 14/92 They ate a Steak to get their health up.

I threw a wave of bones across the floor and they attempted to jump away, but fell down on top of them, dying.

Reset.

"Heh. Yup. The expression of someone dying thrice. Say whats the word that comes after thrice? Frice? Heck if I know. Care to help me find out?"

Frisk grumbled and lashed out without technically starting a "Fight".

I dodged her knife with a smirk.

My left eye started to glow bright blue and I picked up Frisk, crashing her down into some bones and subtracting a lot of health.

She quickly stuffed a piece of steak in her mouth, regaining it back decently.

I tossed her backward with magic, I heard bones snap. It was a sickly sight, furthermore she had exactly 10 HP. Oh yes, she was having a really bad time.

I then realized Her locket had unlatched from the impact. Really its a wonder I noticed it at all. I frowned internally, (considering my face is frozen in a smile) and studied it. That wasn't a proper picture, it was glowing red! And was something... Moving?

I used magic to keep Frisk down as I walked cautiously towards her.

Now at a closer proximity I could see clear as day, there was a person inside the locket! It was odd. It seemed misty, definitely not solid. Was it a form of soul? What was it doing in there? It seemed to be pounding on whatever separated it from me, trying to escape. Odd. Why did it seem so similar?

Then it hit me like a brick.

Frisk wasn't... Frisk.

The "thing" inside the locket looked strikingly similar to Frisk, but how was this possible?

"Frisk" laughed, it was the first time she had actually made an audible sound-besides the crunch of broken bones-this whole battle.

"I see you have discovered a little prized possession of mine." She gaze me a crazed smile.

"You see i've possessed Frisk, locked her very being inside this locket. Although, she can still see out of it. She watched as I broke Mettaton down to wires. As I melted Undyne's soul slowly and painfully. As I murdered the "old lady" who got you to make a promise. As I KilLeD Y0uR bRotHeR!"

I looked at her with a glowing blue eye. At the very back of my mind, there were huge blue stop signs, telling me that I was playing into a trap. Unfortunately it was at the very back and I was blinded by pure rage.

"Frisk" ate raw noodles hurriedly, regaining her health completely.

I attacked.

I let out my Gaster Blasters, I flung bones, I smashed her into walls. Soon she was down to a literal 1/92 with no more items.

I was panting now, but at that moment I could feel nothing but rage and sadness.

Before I could make the final blow "Frisk" spoke,

"Well Sansy. Nice meeting you. Now if you'll excuse me a second I will be right with you."

Suddenly "Frisk" stabbed her locket with her knife, the soul thing flew free. It seemed to go into the human's body, pushing something else out. Frisk(?) fell to the ground in a faint.

A black mass of being seeped out of her, it formed a gruesome human figure that had the kind of smile you see on the faces of insane cartoon characters. It spoke in odd pitches, going from insanely high to darkly low.

"Hehehehehehehe. LoOk aT WhAT YoU'v DoNE SaNs. FrIsK Is oN ThE BrIdgE oF DeAtH AnD ItS AlL YOUR FaUlT. YoU ReMEmBeR ThE LAsT TiMLiNe CoRrEct? FrIsK wAs A PeRfECT CHiLd. KiNd, SMaRt, SeLfLeSS, CaRiNG. WhY yOu TwO WeRe RaTHeR GoOd FrIEndS! ThEn I StArTEd InVAdiNg ThEiR dReAMs! POiSoNiNg HeR ThoUgHtS! ShE LEt hEr WaLlS DoWn JuSt EnOuGh FoR Me tO tAkE OvEr! I rEsEt YoUr "HaPpY eNdInG" AnD StARtEd tHiS GeNOciDe RuN. Hehehehehehe. YoU JuSt KiLleD YoUr FrIeNd!"

She popped up in front of me, in my way of getting to Frisk, an insane smile on her face.

Without thinking I summoned a bone and threw it out of rage towards the demonic spirit. I watched as the bone left my hand, headed for the demon, I watched the demon move, allowing the bone to puncture Frisk's skin and take away her 1 HP.

I collapsed to my knees in shock. Everything was sinking in, Frisk had been possessed. She wasn't evil at all. She had watched as I killed her. Over. And Over. And Over. The demonic being gave an insane laugh and disappeared.

I looked down at her in sorrow, "H-hey kiddo, y-you can reset n-now... P-please? Oh F-Frisk I'm s-so sorry! F-Frisk...?"

I shook her limp corpse, begging her to just load a file. I clutched at her clothes, trying to laugh it off.

"Heh. Y-you got me. R-real f-funny Frisk. Uh, j-jokes over n-now. You can r-reset."

Tears were streaming from my eye sockets now, why wouldn't they just load a darn Save!

Suddenly Frisk's eyes opened just a crack, and a small smile adorned their face. I gasped in surprise and put my skeletal hands over my mouth as my breathing picked up.

"S-Sans...?" Her voice was weak and silent.

I hugged her and whispered, "Frisk... You're alive! I'm so so so sorry Frisk!"

She smiled and put her arms on my back, in an odd, limp hug.

"M-my DETERMINATION allowed me to linger among living for a couple minutes. Sans. Once I die I'm going to do a full reset. It'll go back to when I first landed on those buttercups. Sans... I'm going to make sure you all get the ending you deserve. Please... Have hope ok? Go ahead and be a lazybones," they cracked a smile at the pun and i gave a very small chuckle. "But don't be a lazybones for the reasons you were previously. Don't look so surprised. Please, don't force yourself to be happy."

She gave me a weak stern glare,"you and I need to talk when we get the chance."

She sighed. "See you on the flipside Sans."

She went completely limp, I watched her soul rise out of her body, and shatter.

A second later I saw the flash of white and the pain in my skull(which was more intense because of it being a Full Reset.) I was on the couch in my home eating cold spaghetti, with Papyrus demanding I pick up my darn sock. It took everything in me to not run up to him and demand he never leave me again.

I finished my odd breakfast and told Papyrus I was going on my patrol.

I stepped out into the cold, snowflakes landing on my bare skull. I smiled softly. Everything was going to be ok.

{about 2 hours later}

I saw the doors open, right on time. I hid in the huge trees and studied Frisk carefully for any sign she was possessed by that monster again. I couldn't find anything. She was smiling brightly and skipped ahead, that was new. She looked overly excited to do something. Last Pacifist Run(A.N: he's talking about the run she did before the Genocide Run) she had simply walked, and she had looked a bit at war with herself, as well as scared and a little happy. I'm good at reading people.

I face-palmed myself, shes probably happy to see YOU ya dofus.

I grinned and followed her through the trees, when she skipped over the stick I teleported on and off it, just to see her spin around with a scared expression, which morphed into a knowing grin. She looked around hoping to see me, but when i wanna be hidden, I stay hidden. So she kept on skipping.

Once she arrived at the bridge and "wall" she stopped, staring at the logs fondly.

Before I teleported behind her I positioned the whoopee cushion under my jacket.

I spoke to her softly, "don't ya know how to greet a long lost friend?" I spread my arms wide for a hug.

She immediately lept onto me happily, triggering the whoopee cushion. She burst out in hysterical laughter, I started to laugh too. Soon we were clutching each other in a hug, laughing our faces off with tears in our eyes.

When the chaos died down Frisk spoke, "I promise Sans. I promise you I'll do right this time. I swear it."

I grinned, ruffling her hair, "I'm sure you will. And this time, please tell me if your getting nightmares."

She nodded. "I will."

I smirked, "I hear Papyrus, we better get to that conveniently-shaped lamp." I winked.

She nodded, giving me one last hug and skipping off to hide.

I smiled fondly as I raced after her, I could tell we were going to have a GOOD time. This happiness filled me with DETERMINATION


	2. Grillbys

**OH MY GOOOOOOSH GUYS I AM SO FLIPPIN HAPPY RIGHT NOW! WHEN I SAW HOW MANY FAVOURITES I GOT I JUST IMPLODED! OH. MY. GOOOOOOOOSH. THERE ARE CURRENTLY 9 FAVOURITES AND FOUR FOLLOWS. OH. MY. GURD. AAAAAAHHHHHHHHH! Ok... Deep breaths... Onto business. I'm gonna upload for scenes like this one only. I thought about doing one with the Papyrus and Undyne battle but I kinda want this story to just zone in on Sans and Frisk and their friendship. So ya. And i wont do ever single teensy tiny thing, otherwise the uploads would be three paragraphs long. :| so ya. Things when they just kinda sit down and talk for a bit. I think my next upload will be on their conversation at the MTT hotel thing. So ya. THANK YOU GUYS SO MUCH FOR THE FAVS AND FOLLOWS, THEY MAKE MY DAY! However i have a total of 0 reviews and i'm kinda hoping to get some feedback...? So plz review :3**

Sans and Frisk's Grillby's talk.

Frisk's POV

I arrived at the little cave where Sans was waiting in his little station, well one of his little stations. I first went to talk with Monster Kid, not wanting to be rude by ignoring them. Afterwards I spoke with the fish man and the Echo Flower.

I spun on my heels and walked towards the glowing star that only I could see, a Save. Sans watched me do this, I could feel his stare on my back as I seemingly touched nothing, regaining my health and was filling me with DETERMINATION.

Once I approached him he grinned and said, "What? The more jobs the merrier. Plus, that means more breaks." He gave me a wink accompanied by a knowing grin, which I returned.

"Howsabout we go to Grillbys eh? I'm famished."

I smiled and nodded.

He gave me a joking smile, "alright if you insist, I will pry myself away from my work."

I giggled and gestured towards the hallway to my right, I knew he would wanna take his shortcut. I never figured out how he got to places so fast.

Sans just chuckled and whispered, "I'll let you in on a little secret. My "shortcuts" aren't shortcuts. Honestly I'm not sure how you haven't figured it out yet. I can teleport."

I gaped at him, everything was clicking into place, I face palmed myself for my stupidity.

I gave him a smile and said, "alrighty mister Teleportation Man, lets go."

"Alright miss Time Travel Lady, off we go."

We gave each other secret-keeping grins.

I stumbled somehow, suddenly we were standing at the entrance in Grillbys.

Everyone greeted Sans, just like last time, this time I noticed him set the whoopee cushion down, and before I sat on it I moved it from my seat onto his. His surprised look when he sat down on it was priceless.

"Oh, be careful where you sit Sans. Weirdos like to put whoopee cushions on the seats." I gave him a mischievous grin, upon which he bursted into hysterical laughter.

Once things calmed down, Sans asked me what I wanted to eat, I told him I would like a "burg."

He chuckled and asked Grillby for two burgers.

We sat in silence for a while, reliving the memories of this place and the first conversation we had in the first timeline.

Sans eventually broke the silence, "so what do you think of my bro this timeline?"

I replied saying I thought Papyrus was cool, afterall the dude is dedicated enough to wear the same outfit everyday, including in the shower. I winked.

He chuckled and before he could reply with a witty comment, Grillby came with our food.

"Ahh here comes the grub." Sans said.

I picked up the ketchup bottle, "want some ketchup?" I asked with a grin.

He broke into laughter. When he finally caught his breath he said, "pass. Bone-appetite" he winked.

I chuckled and started to eat.

He spoke again after about a minute of silence, "remember how Flowey whispered stuff to Pap in the other timelines? Well the buggar is doing it again, so just be careful, alright?"

I nodded, my mouth full.

"Anyways I gotta go," he grinned, "cant believe I let you pull me away from work for that long."

I grumbled about how HE asked ME, Sans simply chuckled.

"Oh and by the way, the food wasn't actually 10 000G. Its just ten. I can pay for it."

I shook my head and gave Grillby 10G for the food.

I turned back to him and said, "its the very least I can do. Expect these little things here and there Sans. And don't stop me from helping. There isn't anything I can do to make up for what I did, so let me help with things please?"

He protested, "you're going to save us all from the barrier, give us a happy ending. Thats payment enough. Besides, Chara did it, not you."

"...If Chara suddenly turned good and offered to help let you guys out, would you still completely trust her?"

"Well... No, but you're not Chara! You're Frisk! The first time you came down you genuinely wanted to help people! And you did it! Then Chara interfered. The fact that shes an evil devil-child doesn't affect you."

"... Thanks Sans."

"Anytime."

I gave him a tight hug, when I opened my eyes, I was hugging the echo flower in the cave and Sans was at his post.

I looked over at him, he winked at me, causing me to giggle.

I waved as I walked past him into the next cave. He just smiled.

I looked forward, I had a big adventure ahead of me, but the happiness from talking with Sans filled me with determination.


End file.
